It’s fascinating to see what people knew a hundred years ago about the relationship between diabetes and the foods they ate. Here’s a Q&A on this topic in a 1917 magazine:
Question: Can diabetes be avoided by a proper diet? If so, what food should one avoid to escape the disease? I was told by a physician that diabetes was often inherited, but I want to try to escape it if it depends upon me. –E.L., New York
Answer: No one can answer definitively your question in regard to avoiding diabetes. There is a general impression among physicians that diabetes is, to a certain extent, a diet disease; that is, it has been brought on through faults of diet.
This introduces the personal element. Why does one man eating a certain diet have diabetes and another man eating the same diet not have it? The answer is that one man is resistant and the other non-resistant; but this does not solve the problem.
I believe that if we would eat less carbohydrates, especially sugars, we would be less liable to diabetes. I would advise a simple, wholesome diet such as I would give any person who wishes to lead a correct life from the dietary point of view. I would emphasize the importance of avoiding the use of tea, coffee, chocolate, and tobacco. Sugar cakes, ice cream, pudding, and things of that kind would not enter into my diet scheme. Diabetes is not inherited, but the tendencies which make it possible may be.
Good Housekeeping (September, 1917)